Rotary filter



H. D. GRANT ROTARY FILTER I Filed Sept. 24, 1934 2 Sheets-Sheet 1 a a /616K02 Z wk 1 Z March 2, 1937. H. D. GRANT I 2,072,586

ROTARY FILTER Filed Sept. 24, 1934 2 Sheets-Sheet 2 45 site side.

PATENT OFFICE 2,072,686 norm! mm na uanarmtomsnammm,

amonflonoflllinols aflgnor mm. Harvey. 111.,

Application se tum :4. 10:4, Serial No. 145.190

1 Claim. (01. 210-201) This invention relates to filters, particularly to rotary filters One of the objects of the present, invention isto provide animproved rotary filter. v 5 ,A further object of the invention is to provide an improved knife or scraper mechanism adapted vely to approach nearer and nearerthesurfaceofthefiltertoeifectremoval of material therefrom.

A further object of the invention is to provide a knife m which is adapted to approach VeIyWard the filtering surface and finally to retract therefrom automatically. Other objects, advantages and capabilities of the invention will appear from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings, in which Figure lisasideelevatlonofarotaryfilter my invention:

Fig.2 is a fragmentary elevational view show- .ithe knife-operating mechanism on a larger e.

5 line 3-8 of Fig. 2, and

4 is a sectional detail knife edge in operation.

Referring to the drawings, the reference numeral ll dtes a filter drum ofknown type in which the filtering surface is provided around the cylindrical wall of the drum. The cylindrlcal wall may suitably'compri'se a' perforated wall ll over which is spread afine wire mesh screen If supporting and covered by a,v suitable 5 fabric II. On the inner side of the perforated wail H the filter vdrum is provided with pockets it which communicate through pipes II with a hollow trunnion IS. The hollow trunnion l5 communicates with the interior of a bearing 40 member II, which in turn communicates with a discharge pipe ll to which vacuum may be lll l ed in the usual manner. It will be understood that the drum II is supported upon the trunnion II and another trunnion on the oppo- The filter drum II is partly immersed in liquid contained inia tank ll, which preferv 'ably conforms fairly closely to the shape of'the ,drum. This tankissupportedonarectangular rame is, which in turn rests on' suitable foundazotionsll.

In the normal operation of the filter, vacuum istlm edtothepipel'landthedrum "is rotated by suitable mechanism. The drive bf thedrum maysuitably be by means of ane1ectrio motor 2|, gear reducing lmit I2, intermeviewshowing the -filter fabric II.

m. a 1 sectional detail view takenon the diate appropriate drive elements, worm II and worm gear 24. The drive for the drum is located on the opposite side from that shown in Pig. 1 and is, ntly, shown in dotted lines inthisfigure. Thatiathewormgearlland partsareontheothersideofthe, filter away from the hollow trunnion II and when the motor II is started, vacuum applied to the pipe l1 and liquid containing solid matter wardLv through the 'filter fabric l2 into the chambers II, from whence it bypipes ll into the discharge pipe ll. At the same time a 'layer' of solid material builds up upon the This deposit is sucked dry by means of air entering through it into the chambers ii. The rotation of the drum takes place in the direction of the arrow shown in Fig. 1, and to continue filtering it is n to remove the solid deposit from the filter. This may suitably be effected by means of a knife 25, to which the present invention particular y relates.

It will be understood that there are many kinds of rotary filters and that I do not intend to be limited to the particular type of filter described herein, since my invmtion is applicable is placed'within-the tank ll, liquid is drawn ingenerally to any appropriate type of rotary filter.

In a preferred. operation of a rotary filtersuch as has been described so far, a suitable precoat is first built up upon the filter fabric l2. This precoat maybe of any known or suitable type and the particular precoat employed for any particular purpose will depend upon various considerations, such as price at the locality, inertness of the pre-ooat and the beneficial effects which are necessary in the case of the specific filtration. Among the precoat materials wlrlch may be used are variousforaminous and granular materials such as some clays, fullers earth, diatomaceous earth and the like. The precoat 'may suitably be built up upon the filtering surface of the drum before the main filtration operation ,and one convenient way of doing this' is to supply a slurry or suspension of the precoat to the tank It and'operate'the filtration process -untll the desired thickness of precoat is attained.

When this is being done, the knife 25 should be retracted in a manner which will be more readily understood hereinafter.

The knife I! may suitably comprise a sharpened blade which extends across the face of the drum ll at a point where the periphery of the drum is descending into the liquid in the tank I8. The

blade II is so located that the material which it shaves or skins from the periphery of the drum l0, falls'clear of the tank It into any suitable re ceptacle (not shown), therebeneath. The blade ll is preferably supported on a plurality of fingers which are rigidly mounted upon a bar 21. The bar 21 is rotatably mounted on a plurality of bearings 28 which are rigidly supported on a cross beam 20 which extends from one side of 10 the filter to the other. The beam 29 is supported at both ends by means of legs 30 which are rigidly mounted upon the frame It.

' At one end the bar 21 has rigidly mounted thereon a lever 3| which extends downwardly. 5 At its lower end the lever 3| carries a forked member If having bifurcations one on each side of a bar 31. Each of the bifurcated members of the forked member 32 is provided with a'slot 34, which slots extend in the axial direction of the 20 lever ll. The slots 34 receive pins 35 whichproiect laterally from the bar 38. The bar 38 is mounted in bearings 30 for free sliding move ment in the longitudinal direction. The bar 88 is held against rotation by suitable means, for example, by means of set screws 31 carried by the bearings 30 which extend into key-ways 38 in said bar. The bearings 36 are suitably supported from a base 30 which is rigidly mounted on the frame It. Between the forked member 32 and the adiacent bearing 38 the bar ll is surrounded by a coil spring 40 which abuts against said bearing II and against a washer 4| held in fixed position on the bar it by means of an adjustable nut 42 threadedly mounted thereon. It will be seen from Figs. 1 and 2 that the spring 40 forces the bar 38 to the left and tends to move the knife 28 away from the filtering fabric I2.

Between the bearings 38 the bar It has rigidly mounted thereon a roller 43. This roller is adapted to engage a cam 44 rotatably mounted on a shaft 40 rotatably mounted on a bearing 52. A clutch member 53 is slidably and non-rotatably mounted on the shaft 45 and is adapted to be actuated by a lever 54. By means of this lever 45 the clutch member It may be brought into and out of operative engagement with a comple-' mental-y clutch member 55, which is rigidly mounted on a shaft which is in alignment with the shaft 4!. The shaft 50 is the output 0 shaft of a gear reducing mechanism 46 which is also mounted on the frame It. The input shaft 41 carries a sprocket wheel 40 over which runs a chain 40. This chain 49 rides on a large sprocket wheel 50 which is mounted on the trunnion I l. When the drum l0 rotates, the sprocket wheel is is rotated by the chain". The result is that shaft, 50 and, when the clutch members It and II are engaged, the cam 44, are rotated at a very slow speed, this rotation occurring in the clockwise direction, as viewed in Fig. 2. The cam rotating in the direction indicated and riding on the roller 43, which is pressed against it by the spring 4|, the roller and consequently 5 the bar SI is progressively forced to the right while the drum I0 is being rotated. This movement is very slow and it results in a still slower movement of the knife 25 toward the filtering surface I! and the material de ited thereon. 7 It is ordinarily preferred that t e'movement of the knife II towards the drum I should not exceed 0.006 inch per revolution of the drum. The movement of the knife 2! towards the filtering surface of the drum continues progressively un- 15 til theroiler 43 arrives at the fall II of the cam 44, a condition which is imminent in Fig. 2. A

further slight rotation of the cam 44 from the position shown in Fig.2 allows the roller 43 to ride down the cam fall 5| under the infiuence of the spring 40. This movement causes the knife 25 to move away from the filter drum so that a new precoat layer may be built up thereon.

The clutch member 53 carries an integral pinion- 51 which is brought into engagement with a pinion 58 rigidly mounted on a shaft 59. The shaft 59 is mounted in a bearing 00 and is pro-' vided with a hand wheel 8|. When the clutch members and are brought into engagement the pinions Ihand 50 are disengaged. It will thus be seen thatthe cam 44 may be automatically driven by the'rotation of the filter drum or, they may be manually actuated by means of the wheel 6|. a It will be understood that the highest point on the cam 44 is such that the knife 25 does not come into contact with the fabric l2, injury thereto being thereby avoided.

The operation is as follows: The knife 25 being at approximately its farthest position from the drum I0, with the bar 33 in its extreme left position, as viewed in Fig. 1, the roller 43 rests firmly against the lowest partof the cam 44. The clu lever 54 is thrown to disengage the clutch members and a'slurry of a suitable preooat material is applied to the tank It. vacuum is'applied to the pipe l1 and the motor 2| is started so that the drum it rotates. The liquid part of theslurry is drawn through the filter fabric l2 and passes away through pipe II. The precoat material builds up as a deposit on the peripheral surface of the drum It. This operation is continued until the precoat layer has attained a suitable size, for

example, a thickness of 1" or 1 which brings the surface of the preooat layer close to the cutting edge of the knife 25. The slurry then drained from the tank I0 and the knife 25 slowly advanced by the hand wheel 0| until the precoatlayer is shaved and trued by the knife. The material to be filtered is now supplied to the tank II and the lever 54 is thrown to engage the clutch members and disengage the pinions I1 and I0. With-continued rotation of the drum l0, the cam 44 is slowly rotated with the result that the knife 2| moves very slowly towards the filtering surface of the drum it. As indicated above, this movement preferably does not exceed 0.005 inch per revolution ofthe drum I0. The result is that the material being filtered, which builds up as. a' deposit on the drum II as the drum rotates, is continuously removed by the knife 25 and in addition to the solid material being. filtered, a thin layer, ordinarily not exceeding 0.005 inch of precoat is also removed. In this way a new surface of' precoat is always presented tocthe liquid in the tank It. This continues until roller 43 r ms past the fall II of thecam44,wh pontheknife 28 returns to its most remote sition with respect to the drum ll. When this occurs'the preooat layer should be built up again in the manner above described.

It is to benoted that the cam '44 is actuated continuously with the rotary element of the filter during the filtering operation. The'cam 44 is contoured so that the knife 2! feeds substantially uniformly and at a very slow rate towards the filtering surface. As a result of this structure the knife takes a fine cut in the form of aspiral and the knife is held rigid in cutting position without any tendency to vibrate. A new precoat surface is thereby presented to the liquid in the tank ll and high filtering emciency is maintained through the whole filtering operation.

Although the invention has been disclosed in connection with. the specific details of a preferred embodiment thereof, it must be understood that such details are not intended to be limitative of the invention except in so far as set forth in the accompanying claim, Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

A filter comprising a rotary drum, the cylindrical periphery of which is the filtering surface, a

CERTIFICATE Patent No. 2,072,586.

HOWARD D. GRANT.

It is hereby certified that error appears in the printed specification 7 of the above numbered patent requiring correction as follows:

knife extending across said surface, means providing a suspended pivotal mounting for said knife, a long lever for actuating said knife to cause I OF CORRECTION.

Page 2,

second column, line 50, for the word "applied" {first occurrence, read supplied; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

I Signed and sealed this 6th 'day of April, A. D. 1937.

Seal) Henry Van Arsdale Acting Commissioner of Patents.

March 2 1957.

and high filtering emciency is maintained through the whole filtering operation.

Although the invention has been disclosed in connection with. the specific details of a preferred embodiment thereof, it must be understood that such details are not intended to be limitative of the invention except in so far as set forth in the accompanying claim, Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

A filter comprising a rotary drum, the cylindrical periphery of which is the filtering surface, a

CERTIFICATE Patent No. 2,072,586.

HOWARD D. GRANT.

It is hereby certified that error appears in the printed specification 7 of the above numbered patent requiring correction as follows:

knife extending across said surface, means providing a suspended pivotal mounting for said knife, a long lever for actuating said knife to cause I OF CORRECTION.

Page 2,

second column, line 50, for the word "applied" {first occurrence, read supplied; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

I Signed and sealed this 6th 'day of April, A. D. 1937.

Seal) Henry Van Arsdale Acting Commissioner of Patents.

March 2 1957. 

